The Cape eagle-owl is nocturnal, roosting by day among rocks, in sheltered rock ledges, or in large rock crevices and caves. They may also roost in trees or even on the ground amongst dense bushes. They have been rarely found roosting in cities like
Johannesburg and
Pretoria. Often a male and female can be found roosting together, especially just before the breeding season. The predominant prey for the species is
mammals. These can range in size from
shrews and small
rodents to animals the size of
hyraxes which are heavier than the birds themselves. Other important prey can include other
birds, up to the size of
francolins and
hamerkops. Opportunistically, the Cape eagle-owl will supplement its diet with
reptiles,
frogs,
scorpions,
crabs and large
insects.
Mole rats are locally often a favorite prey item and 1 to 3 mole rats can be taken each night during the breeding season. A pair with half-grown chicks requires about per night. Hunts are from prominent perches, with the owl gliding in descending flight after prey and killing them with their powerful talons or bill. These territorial owls may exist in close proximity where populations are dense, occurring at . The male advertises the territory by calling, with duets being rare in this species. During courtship, the male bows and hoots in front of the upright, silent female. The nest may be a shallow scrape on a sheltered rock ledge, in a rock crevice, in a cave or even on the ground underneath a dense bush. More rarely, large stick nests made by other birds or the tops of large bushes are used. Normally the Cape eagle-owl breeds every year, but may breed in alternate years. Usually 2 (rare 1 or 3) white eggs are laid, measuring x and weighing , at 2-day intervals. The female incubates for 34 to 38 days, while the male feeds her. The young hatch at intervals of up to 4 days. New hatchlings weigh , then weigh at 20 days and are nearly adult size by 40 days. The female broods the chicks, feeding them with small piece of meat brought by the males. At 11–13 days old, the chicks sprout buff down from the mesoptile plumage. Although at times of plenty, all chicks may survive, usually the second, smaller chick dies from starvation. By 17 days, the female occasionally leaves the nest but still roosts near the young. By 3 to 4 weeks, the mother stops coming to the nest but still roosts with the young. If the nesting site permits, the young start walking away from the nest at around 45 days old and can fly well by 70–77 days. The young are cared for a total of 6 months and reach sexual maturity the following year. ==Status==